Magnesium dichloride-ethanol adduct and catalyst components obtained therefrom

ABSTRACT

A MgCl 2 ·mEtOH·nH 2 O adducts, where 3.4&lt;m≦4.4, 0≦n≦0.7, characterized by an X-ray diffraction spectrum, taken under the condition set forth above, in which, in the range of 2θ diffraction angles between 5° and 10°, at least two diffraction lines are present at diffraction angles 2θ of 9.3±0.2°, and 9.9±0.2°, the most intense diffraction lines being the one at 2θ of 9.3±0.2°, the intensity of the other diffraction line being less than 0.4 times the intensity of the most intense diffraction line. Catalyst components obtained from the adducts of the present invention are capable to give catalysts for the polymerization of olefins characterized by enhanced activity and/or porosity with respect to the catalysts prepared from the adducts of the prior art.

This application is the U.S. national phase of International ApplicationPCT/EP2003/009282, filed Aug. 21, 2003.

The present invention relates to magnesium dichloride/ethanol adductswhich are characterized by particular chemical and physical properties.The adducts of the present invention are particularly useful asprecursors of catalyst components for the polymerization of olefins.

MgCl₂·alcohol adducts and their use in the preparation of catalystcomponents for the polymerization of olefins are well known in the art.

Catalyst components for the polymerization of olefins, obtained byreacting MgCl₂·nEtOH adducts with halogenated transition metalcompounds, are described in U.S. Pat. No. 4,399,054. The adducts areprepared by emulsifying the molten adduct in an immiscible dispersingmedium and quenching the emulsion in a cooling fluid to collect theadduct in the form of spherical particles. The number of moles ofalcohol per mole of MgCl₂ is generally 3. In order to render thecatalyst suitable to produce non-fragile polymer particles, the alcoholcontent of the adduct is lowered, before reaction with the titaniumcompound, to values in the range of 2–2.5 moles. As a downside, however,the catalyst activity becomes too low.

In WO98/44009 are disclosed MgCl₂·alcohol adducts having improvedcharacteristics and characterized by a particular X-ray diffractionspectrum, in which, in the range of 2θ diffraction angles between 5° and15°, the three main diffraction lines are present at diffraction angles2θ of 8.8±0.2°, 9.4±0.2° and 9.8±0.2°, the most intense diffractionlines being the one at 2θ=8.8±0.2°, the intensity of the other twodiffraction lines being at least 0.2 times the intensity of the mostintense diffraction line. Said adducts can be of formulaMgCl₂·mEtOH·nH₂O where m is between 2.2 and 3.8 and n is between 0.01and 0.6. The catalyst components obtained from these adducts have anincreased activity over those obtained from the adducts of U.S. Pat. No.4,399,054. Also in this case the dealcoholation of the adducts beforethe reaction with the titanium compound (example 6) increases theporosity of the final catalyst but makes its activity much lower.

EP-A-700936 describes a process for producing a solid catalystcomponents for the polymerization of olefins which comprises the (A) thepreparation of a MgCl₂·4EtOH solid adducts by means of spray-cooling aMgCl₂ and ethanol mixture; (B) partly removing the alcohol from theabove-obtained solid adduct to obtain an adduct containing from 0.4 to2.8 mol of alcohol per mol of MgCl₂. FIG. 2 of the said European PatentApplication shows a typical X-ray diffraction spectrum of the adductsprepared in (A). The highest peak occurs at 2θ=8.8°; two less intensepeaks occur at 2θ=9.5 to 10° and 2θ=13°, respectively. The adductobtained in (B) is characterized by an X-ray diffraction spectrum inwhich a novel peak does not occur at a diffraction angles 2θ=7 to 8° ascompared with the diffraction spectrum of the adduct obtained in (A), oreven if it occurs, the intensity of the novel peak is 2.0 times or lessthe intensity of the highest peak present at the diffraction angles2θ=8.5 to 9° of the diffraction spectrum of the adduct obtained in (B).FIG. 3 shows a typical X-ray diffraction spectrum of the adductsprepared in (B) and thus containing about 1.7 moles of ethanol. Thehighest peak occurs at 2θ=8.8°; other peaks occur at 2θ=6.0 to 6.5°,2θ=9.5 to 10° and 2θ=11 to 11.5°. The applicant has now found newMgCl₂·mEtOH adducts having specific chemical and physical properties.The adducts of the present invention can be used to prepare catalystcomponents for the polymerization of olefins by reacting them withtransition metal compounds. Catalyst components directly obtained fromthe adducts of the present invention are capable to give catalysts forthe polymerization of olefins characterized by enhanced activity withrespect to the catalyst of the prior art derived from non-dealcoholatedadduct. An additional advantage is obtainable by the dealcoholation ofthe adducts which allows the preparation of catalysts with a higherporosity with respect to the prior art. Therefore, with the adducts ofthe invention it is possible to modulate the properties of the finalcatalyst in order to obtain, in comparison with the catalyst of theprior art, either a higher porosity and same activity or a higheractivity with the same porosity level.

The present invention therefore relates to MgCl₂·mEtOH·nH₂O adducts were3.4<m≦4.4, 0≦n≦0.7, characterized by an X-ray diffraction spectrum,taken under the condition set forth below, in which, in the range of 2θdiffraction angles between 5° and 10°, at least two diffraction linesare present at diffraction angles 2θ of 9.3±0.2°, and 9.9±0.2°, the mostintense diffraction lines being the one at 2θ of 9.3±0.2°, the intensityof the other diffraction line being less than 0.4 times the intensity ofthe most intense diffraction line.

Preferably, 3.8<m≦4.2, more preferably 3.9<m≦4.1 and 0≦n≦0.4. Preferablythe intensity of the peak at diffraction angles 2θ of 9.9±0.2° is lessthan 0.3 times the intensity of the most intense diffraction line.Preferably an additional diffraction line at diffraction angles 2θ of8.1±0.2° having an intensity of less than 0.7 times the intensity of thediffraction line at diffraction angles 2θ of and 9.9±0.2° is present.Moreover, in some instances an additional diffraction line atdiffraction angles 2θ of and 9.1±0.2° is present. This latter line hasan intensity of from 0.6 to 0.9 times, preferably from 0.6 to 0.8, theintensity of the most intense diffraction line in the range of 2θdiffraction angles between 5° and 10°.

Particularly interesting are the adducts of the invention showing, inthe DSC profile taken under the conditions set forth below, only onemelting peak (Tm) in the range 90–105° C. g having an associated fusionenthalpy generally lower than 125 J/g and preferably lower than 110 J/g.If additional peaks in the region below 80° C. are present, the fusionenthalpy associated to them is lower than 30% of the total fusionenthalpy, preferably lower than 20 and more preferably lower than 10%.The DSC analysis is carried out using the apparatus and the methodologydescribed hereinafter.

One of the preferred methods for preparing the adducts of the presentinvention comprises dispersing the particles of magnesium dichloride inan inert liquid immiscible with and chemically inert to the moltenadduct, heating the system at temperature equal to or higher than themelting temperature of MgCl₂·ethanol adduct and then adding the desiredamount of alcohol in vapour phase. The temperature is kept at valuessuch that the adduct is completely melted. The molten adduct is thenemulsified in a liquid medium which is immiscible with and chemicallyinert to it and then quenched by contacting the adduct with an inertcooling liquid, thereby obtaining the solidification of the adduct.

The liquid in which the MgCl₂ is dispersed can be any liquid immisciblewith and chemically inert to the molten adduct. For example, aliphatic,aromatic or cycloaliphatic hydrocarbons can be used as well as siliconeoils. Aliphatic hydrocarbons such as vaseline oil are particularlypreferred. After the MgCl₂ particles are dispersed in the inert liquid,the mixture is heated at temperatures preferably higher than 95° C. andmore preferably in the range 100–130° C. Conveniently, the vaporizedalcohol is added at a temperature equal to or lower than the temperatureof the mixture.

According to another method, the adducts of the invention are preparedby contacting MgCl₂ and alcohol in the absence of the inert liquiddispersant, heating the system at the melting temperature ofMgCl₂-alcohol adduct or above, and maintaining said conditions so as toobtain a completely melted adduct. In particular, the adduct ispreferably kept at a temperature equal to or higher than its meltingtemperature, under stirring conditions, for a time period equal to orgreater than 2 hours, preferably from 2 to 15 hours, more preferablyfrom 5 to 10 hours. Said molten adduct is then emulsified in a liquidmedium which is immiscible with and chemically inert to it and finallyquenched by contacting the adduct with an inert cooling liquid therebyobtaining the solidification of the adduct. It is also preferable,before recovering the solid particles, to leave them in the coolingliquid at a temperature ranging from −10 to 25° C. for a time rangingfrom 1 to 24 hours. Particularly in this method the solidification ofthe adduct in spherical particles can be obtained by spraying theMgCl₂-alcohol adduct, not emulsified, in an environment having atemperature so low as to cause rapid solidification of the particles.

All these methods provide solid adducts having a substantially sphericalmorphology and average diameter comprised between 5 and 150 μm which arevery suitable in the preparation of spherical catalyst components forthe polymerization of olefins and in particular for the gas-phasepolymerization process. With the term substantial spherical morphologyare meant those particles having a ratio between the greater and smalleraxis equal to or lower than 1.5 and preferably lower than 1.3.

In order to not to exceed the maximum value of n contemplated by theabove formula a particular attention should be paid to the water contentof the reactants. Both MgCl₂ and EtOH are in fact highly hygroscopic andtend to incorporate water in their structure. As a result, if the watercontent of the reactants is relatively high, the final MgCl₂-EtOHadducts may contain a too high water content even if water has not beenadded as a separate component. Means for controlling or lowering thewater content in solids or fluids are well known in the art. The watercontent in MgCl₂ can be for example lowered by drying it in an oven athigh temperatures or by reacting it with a compound which is reactivetowards water. As an example, a stream of HCl can be used to removewater from MgCl₂. Water from the fluids can be removed by varioustechniques such as distillation or by allowing the fluids to become incontact with substances capable to subtract water such as molecularsieves. Once this precautions have been taken, the reaction between themagnesium chloride and ethanol to produce the adducts of the inventioncan be carried out according to various methods.

Upon reaction with transition metal compounds, the adducts of theinvention form suitable catalyst components for the polymerization ofolefins.

The adducts can be reacted as such with the transition metal compoundor, in alternative, they can be subject to a preliminary step ofdealcoholation.

Among transition metal compounds particularly preferred are titaniumcompounds of formula Ti(OR)_(n)X_(y-n) in which n is comprised between 0and y; y is the valence of titanium; X is halogen and R is anhydrocarbon radical, preferably alkyl, radical having 1–10 carbon atomsor a COR′ group wherein R′ is an alkyl radical having 1–8 carbon atoms.Among them, particularly preferred are titanium compounds having atleast one Ti-halogen bond such as titanium tetrahalides orhalogenalcoholates. Preferred specific titanium compounds are TiCl₃,TiCl₄, Ti(OBu)₄, Ti(OBu)Cl₃, Ti(OBu)₂Cl₂, Ti(OBu)₃Cl. Preferably, thereaction is carried out by suspending the adduct in cold TiCl₄(generally 0° C.); then the so obtained mixture is heated up to 80–130°C. and kept at this temperature for 0.5–2 hours. After that the excessof TiCl₄ is removed and the solid component is recovered. The treatmentwith TiCl₄ can be carried out one or more times.

The reaction between transition metal compound and the adduct can alsobe carried out in the presence of an electron donor compound (internaldonor) in particular when the preparation of a stereospecific catalystfor the polymerization of olefins is to be prepared. Said electron donorcompound can be selected from esters, ethers, amines, silanes andketones. In particular, the alkyl and aryl esters of mono orpolycarboxylic acids such as for example esters of benzoic, phthalic,malonic and succinic acid are preferred. Specific examples of suchesters are n-butylphthalate, di-isobutylphthalate, di-n-octylphthalate,diethyl 2,2-diisopropylsuccinate, diethyl 2,2-dicyclohexyl-succinate,ethyl-benzoate and p-ethoxy ethyl-benzoate. Moreover, can beadvantageously used also the 1,3 diethers of the formula:

wherein R⁰, R^(I), R^(II), R^(III), R^(IV) and R^(V) equal or differentto each other, are hydrogen or hydrocarbon radicals having from 1 to 18carbon atoms, and R^(VI) and R^(VII), equal or different from eachother, have the same meaning of R—R^(V) except that they cannot behydrogen; one or more of the R—R^(VII) groups can be linked to form acycle. The 1,3-diethers in which R^(VI) and R^(VII) are selected fromC₁-C₄ alkyl radicals are particularly preferred.

The electron donor compound is generally present in molar ratio withrespect to the magnesium comprised between 1:4 and 1:20.

Preferably, the particles of the solid catalyst components replicatethose of the solid adducts illustrated above, thus showing asubstantially spherical morphology and an average diameter comprisedbetween 5 and 150 μm.

As mentioned before the reaction with the transition metal compound, theadducts of the present invention can also be subjected to adealcoholation treatment aimed at lowering the alcohol content andincreasing the porosity of the adduct itself. The dealcoholation can becarried out according to known methodologies such as those described inEP-A-395083. Depending on the extent of the dealocholation treatment,partially dealcoholated adducts can be obtained having an alcoholcontent generally ranging from 0.1 to 3 moles of alcohol per mole ofMgCl₂ and a porosity (determined with Hg method described below))ranging from 0.05 to 2 cc/g. Among this class particularly interestingare the dealcoholated adducts containing from 1 to 3 moles of alcoholand porosity in the range of 0.15 to 1.5 cc/g. After the dealcoholationtreatment the adducts are reacted with the transition metal compound,according to the techniques described above, in order to obtain thesolid catalyst components. As mentioned before the solid catalystcomponents according to the present invention show a porosity(determined with Hg method) higher than 0.2 cm³/g preferably between0.25 and 2 cm³/g.

Surprisingly, the catalyst components comprising the reaction product ofa transition metal compound with a MgCl₂-alcohol adduct which is in turnobtained by partially dealcoholating the adducts of the invention, showimproved properties, particularly in terms of activity and porosity,with respect to the catalyst components prepared from the dealcoholatedadducts of the prior art. Particularly interesting are the catalystobtained by reacting the transition metal compound with dealcoholatedadducts containing from 1 to 3 moles of alcohol. The so obtainedcatalysts have an higher porosity with respect to the catalyst obtainedby the adducts of the prior art, such as those of WO98/44009, having thecorresponding alcohol content. On the other hand, for the same porosity,the catalyst of the invention are more active than those of the priorart.

The catalyst components of the invention form catalysts for thepolymerization of alpha-olefins CH₂═CHR⁴, wherein R⁴ is hydrogen or ahydrocarbon radical having 1–12 carbon atoms, by reaction with Al-alkylcompounds. The alkyl-Al compound is preferably chosen among the trialkylaluminum compounds such as for example triethylaluminum,triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum. It is also possible to use alkylaluminum halides,alkylaluminum hydrides or alkylaluminum sequichlorides such as AlEt₂Cland Al₂Et₃Cl₃ optionally in mixture with said trialkyl aluminumcompounds.

The Al/Ti ratio is higher than 1 and is generally comprised between 20and 800. In the case of the stereoregular polymerization of α-olefinssuch as for example propylene and 1-butene, an electron donor compound(external donor) which can be the same or different from the compoundused as internal donor can be used in the preparation of the catalystsdisclosed above. In case the internal donor is an ester of apolycarboxylic acid, in particular a phthalate, the external donor ispreferably selected from the silane compounds containing at least aSi—OR link, having the formula R_(a) ¹R_(b) ²Si(OR³)_(c), where a and bare integer from 0 to 2, c is an integer from 1 to 3 and the sum (a+b+c)is 4; R¹, R², and R³, are alkyl, cycloalkyl or aryl radicals with 1–18carbon atoms. Particularly preferred are the silicon compounds in whicha is 1, b is 1, c is 2, at least one of R¹ and R² is selected frombranched alkyl, cycloalkyl or aryl groups with 3–10 carbon atoms and R³is a C₁-C₁₀ alkyl group, in particular methyl. Examples of suchpreferred silicon compounds are methylcyclohexyldimethoxysilane,diphenyldimethoxysilane, methyl-t-butyldimethoxysilane,dicyclopentyldimethoxysilane. Moreover, are also preferred the siliconcompounds in which a is 0, c is 3, R² is a branched alkyl or cycloalkylgroup and R³ is methyl. Examples of such preferred silicon compounds arecyclohexyltrimethoxysilane, t-butyltrimethoxysilane andthexyltrimethoxysilane.

Also the 1,3 diethers having the previously described formula can beused as external donor. However, in the case 1,3-diethers are used asinternal donors, the use of an external donor can be avoided, as thestereospecificity of the catalyst is already sufficiently high.

As previously indicated the components of the invention and catalystsobtained therefrom find applications in the processes for the(co)polymerization of olefins of formula CH₂═CHR in which R is hydrogenor a hydrocarbon radical having 1–12 carbon atoms.

The catalysts of the invention can be used in any of the olefinpolymerization processes known in the art. They can be used for examplein slurry polymerization using as diluent an inert hydrocarbon solventor bulk polymerization using the liquid monomer (for example propylene)as a reaction medium. Moreover, they can also be used in thepolymerization process carried out in gas-phase operating in one or morefluidized or mechanically agitated bed reactors.

The polymerization is generally carried out at temperature of from 20 to120° C., preferably of from 40 to 80° C. When the polymerization iscarried out in gas-phase the operating pressure is generally between 0.1and 10 MPa, preferably between 1 and 5 MPa. In the bulk polymerizationthe operating pressure is generally between 1 and 6 MPa preferablybetween 1.5 and 4 MPa.

The catalysts of the invention are very useful for preparing a broadrange of polyolefin products. Specific examples of the olefinic polymerswhich can be prepared are: high density ethylene polymers (HDPE, havinga density higher than 0.940 g/cc), comprising ethylene homopolymers andcopolymers of ethylene with alpha-olefins having 3–12 carbon atoms;linear low density polyethylenes (LLDPE, having a density lower than0.940 g/cc) and very low density and ultra low density (VLDPE and ULDPE,having a density lower than 0.920 g/cc, to 0.880 g/cc) consisting ofcopolymers of ethylene with one or more alpha-olefins having from 3 to12 carbon atoms, having a mole content of units derived from theethylene higher than 80%; isotactic polypropylenes and crystallinecopolymers of propylene and ethylene and/or other alpha-olefins having acontent of units derived from propylene higher than 85% by weight;copolymers of propylene and 1-butene having a content of units derivedfrom 1-butene comprised between 1 and 40% by weight; heterophasiccopolymers comprising a crystalline polypropylene matrix and anamorphous phase comprising copolymers of propylene with ethylene and orother alpha-olefins.

The following examples are given to illustrate and not to limit theinvention itself.

Characterization

The properties reported below have been determined according to thefollowing methods:

X-ray diffraction spectra were carried out with a Philips PW 1710instrument using the CuK_(α)(λ=1,5418Δ) radiation and equipped with amonochromator, a 40 Kv tension generator, a 30 mA current generator, anautomatic divergence slit and a receiving slit of 0.2 mm. The X-raydiffraction patterns were recorded in the range between 2θ=5° and 2θ=15°with a scanning rate of 0.02° 2θ/18 sec. The instrument was calibratedusing the ASTM 27-1402 standard for Silicon. The samples to be analyzedwere closed in a polyethylene bas of 50 μm thickness operating in adry-box.

The DSC measurement were carried out with a Perkin Elmer instrument at ascanning rate of 5° C./min in the range 5–125° C. Aluminum capsuleshaving a volume of 40 μl filled with the samples in a dry-box were usedin order to avoid hydration of the samples.

Porosity and surface area with nitrogen: are determined according to theB.E.T. method (apparatus used SORPTOMATIC 1900 by Carlo Erba).

Porosity and Surface Area with Mercury:

The measure is carried out using a “Porosimeter 2000 series” by CarloErba.

The porosity is determined by absorption of mercury under pressure. Forthis determination use is made of a calibrated dilatometer (diameter 3mm) CD₃ (Carlo Erba) connected to a reservoir of mercury and to ahigh-vacuum pump (1–10⁻² mbar). A weighed amount of sample is placed inthe dilatometer. The apparatus is then placed under high vacuum (<0.1 mmHg) and is maintained in these conditions for 20 minutes. Thedilatometer is then connected to the mercury reservoir and the mercuryis allowed to flow slowly into it until it reaches the level marked onthe dilatometer at a height of 10 cm. The valve that connects thedilatometer to the vacuum pump is closed and then the mercury pressureis gradually increased with nitrogen up to 140 kg/cm². Under the effectof the pressure, the mercury enters the pores and the level goes downaccording to the porosity of the material.

The porosity (cm³/g), due to pores up to 0.1 mm, the pore distributioncurve, and the average pore size are directly calculated from theintegral pore distribution curve which is function of the volumereduction of the mercury and applied pressure values (all these data areprovided and elaborated by the porosimeter associated computer which isequipped with a “MILESTONE 200/2.04” program by C. Erba.

The DSC measurement were carried out with a METTLER DSC 30 instrument ata scanning rate of 5° C./min in the range 5–125° C. Aluminum capsuleshaving a volume of 40 μl filled with the samples in a dry-box were usedin order to avoid hydration of the samples.

EXAMPLES General Procedure for the Preparation of the Catalyst Component

Into a 11 steel reactor provided with stirrer, 800 cm³ of TiCl₄ at 0° C.were introduced; at room temperature and whilst stirring 16 g of theadduct were introduced together with an amount of diisobutylphthalate asinternal donor so as to give a donor/Mg molar ratio of 10. The whole washeated to 100° C. over 90 minutes and these conditions were maintainedover 120 minutes. The stirring was stopped and after 30 minutes theliquid phase was separated from the sedimented solid maintaining thetemperature at 100° C. A further treatment of the solid was carried outadding 750 cm³ of TiCl₄ and heating the mixture at 120° C. over 10 min.and maintaining said conditions for 60 min under stirring conditions(500 rpm). The stirring was then discontinued and after 30 minutes theliquid phase was separated from the sedimented solid maintaining thetemperature at 120° C. Thereafter, 3 washings with 500 cm³ of anhydroushexane at 60° C. and 3 washings with 500 cm³ of anhydrous hexane at roomtemperature were carried out. The solid catalyst component obtained wasthen dried under vacuum in nitrogen environment at a temperature rangingfrom 40–45° C.

General Procedure for the Polymerization Test

A 4 liter steel autoclave equipped with a stirrer, pressure gauge,thermometer, catalyst feeding system, monomer feeding lines andthermostatting jacket, was used. The reactor was charged with 0.01 gr.of solid catalyst component 0,76 g of TEAL, 0.076 g ofdicyclopentyldimetoxy silane, 3.2 l of propylene, and 1.5 l of hydrogen.The system was heated to 70° C. over 10 min. under stirring, andmaintained under these conditions for 120 min. At the end of thepolymerization, the polymer was recovered by removing any unreactedmonomers and was dried under vacuum.

Example 1

In a vessel reactor equipped with a IKA RE 166 stirrer containing 181.64g of anhydrous EtOH at −8° C. were introduced under stirring 93.26 gr.of MgCl₂ containing 0.3% water. Once the addition of MgCl₂ wascompleted, the temperature was raised up to 108° C. and kept at thisvalue for 3 hours. After that, 1600 cm³ of OB55 vaseline oil wereintroduced and, while keeping the temperature at 108° C., the stirringwas brought to 1500 rpm and kept at that value for two minutes. Afterthat time the mixture was discharged into a vessel containing hexanewhich was kept under stirring and cooled so that the final temperaturedid not exceed 12° C. After 12 hours, the solid particles of theMgCl₂·EtOH adduct recovered were then washed with hexane and dried at40° C. under vacuum. The compositional analysis showed that theycontained 64% by weight of EtOH and 0.4% of water.

The X-ray spectrum of the adduct showed in the range of 2θ diffractionangles between 5° and 10° one main diffraction line present atdiffraction angles 2θ of 9.34° (100), and a side peak around 9,87 (10);the number in brackets represents the intensity I/I_(o) with respect tothe most intense line.

The DSC profile showed a peak at 95.8° C. with an associated fusionenthalpy of 102.3 J/g. The adduct was then used, according to thegeneral procedure, for preparing the catalyst component the propertiesof which are reported in Table 1. The catalyst was then tested accordingto the general polymerization procedure described above and gave theresults reported in Table 2.

Example 2

In a vessel reactor equipped with a IKA RE 166 stirrer containing 181 gof anhydrous EtOH at −6.5° C. temperature were introduced under stirring93.14 g of MgCl₂ containing 0.3% water. Once the addition of MgCl₂ wascompleted, the temperature was raised up to 108° C. and kept at thisvalue for 3 hours. After that, 1600 cm³ of OB55 vaseline oil wereintroduced and, while keeping the temperature at 105.5° C., the stirringwas brought to 1500 rpm and kept at that value for two minutes. Afterthat time the mixture was discharged into a vessel containing hexanewhich was kept under stirring and cooled so that the final temperaturedid not exceed 12° C. After 12 hours, the solid particles of theMgCl₂·EtOH adduct recovered were then washed with hexane and dried at40° C. under vacuum. The compositional analysis showed that theycontained 64.4% by weight of EtOH and 0.4% of water.

The X-ray spectrum of the adduct showed in the range of 2θ diffractionangles between 5° and 10° four diffraction lines present at diffractionangles 2θ of 8.11 (10), 9.41 (100), 9.11 (76) and 9.9° (16); the numberin brackets represents the intensity I/I_(o) with respect to the mostintense line.

The DSC profile showed a peak at 98° C., with an associated fusionenthalpy of 104.4 J/g. The adduct was then used, according to thegeneral procedure, for preparing the catalyst component the propertiesof which are reported in Table 1. The catalyst was then tested accordingto the general polymerization procedure described above and gave theresults reported in Table 2.

Example 3

An MgCl₂—EtOH adduct prepared according to the procedure of Example 1was thermally dealcoholated under nitrogen flow until the content ofEtOH reached 40% b.w,. The so dealcoholated adduct showed a porosity of0.617 cm³/g. Then, said dealcoholated adduct was used to prepare,according to the general procedure, the catalyst component theproperties of which are reported in table 1. The catalyst was then usedin a polymerization test carried out according to the proceduredescribed above. The results are reported in Table 2.

Comparison Example 1

In a vessel reactor equipped with a IKA RE 166 stirrer containing 139.16g of anhydrous EtOH at room temperature were introduced under stirring95.64 gr. of MgCl₂ containing 0.3% water. Once the addition of MgCl₂ wascompleted, the temperature was raised up to 125° C. and kept at thisvalue for 3 hours. After that, 1600 cm³ of OB55 vaseline oil wereintroduced and, while keeping the temperature at 125° C., the stirringwas brought to 1500 rpm and kept at that value for two minutes. Afterthat time the mixture was discharged into a vessel containing hexanewhich was kept under stirring and cooled so that the final temperaturedid not exceed 12° C. After 12 hours, the solid particles of theMgCl₂·EtOH adduct recovered were then washed with hexane and dried at40° C. under vacuum. The compositional analysis showed that theycontained 58.5% by weight of EtOH and 0.3% of water.

The adduct was then used, according to the general procedure, forpreparing the catalyst component the properties of which are reported inTable 1. The catalyst was then tested according to the generalpolymerization procedure described above and gave the results reportedin Table 2.

Comparison Example 2

An MgCl₂—EtOH adduct prepared according to the procedure of Example 1was thermally dealcoholated under nitrogen flow until the content ofEtOH reached 40% b.w,. The so dealcoholated adduct showed a porosity of0.3 cm³/g.

TABLE 1 Ti Mg ID Porosity Example % wt % wt % wt Cm³/g 1 2.9 18.1 12.8n.d. 2 3 18.5 12.5 n.d 3 2.6 17.9 6.7 0.821 Comp. 1 3 14.5 19.4 n.d.Comp. 2 2.8 19.2 6 0.562

TABLE 2 Example Activity I.I: Poured bulk density 1 75 97.6 0.435 2 7297.5 0.42 3 21 96.5 0.32 Comp. 1 58 97.7 0.445 Comp. 2 17.5 96.5 0.325

1. A MgCl₂·mEtOH·nH₂O adduct, wherein 3.4<m≦4.4, 0<n≦0.7, the adducthaving an X-ray diffraction spectrum comprising at least one diffractionline at each diffraction angle 2θ of 9.3±0.2° and 9.9±0.2° with eachdiffraction angle being between 5° and 10°, the diffraction line atdiffraction angle 2θ of 9.3±0.2° being more intense than the diffractionline at diffraction angle 2θ of 9.9±0.2°, and the diffraction line atdiffraction angle 2θ of 9.9±0.2° being less than 0.4 times as intense asthe diffraction line at diffraction angle 2θ of 9.3±0.2°.
 2. The adductaccording to claim 1, wherein 3.8<m≦4.2 and 0<n≦0.7.
 3. The adductaccording to claim 2, wherein the diffraction line at diffraction angle2θ of 9.9±0.2° is less than 0.3 times as intense as the diffraction lineat diffraction angle 2θ of 9.3±0.2°.
 4. The adduct according to claim 1,further comprising a diffraction line at diffraction angle 2θ of8.1±0.2°, the diffraction line at diffraction angle 2θ of 8.1±0.2° beingless than 0.7 times as intense as the diffraction line at diffractionangle 2θ of 9.9±0.2°.
 5. The adduct according to claim 1, wherein theadduct has only one melting peak between 90–105° C. in a DSC profile. 6.The adduct according to claim 5, wherein the melting peak has anassociated fusion enthalpy lower than 125 J/g.
 7. The adduct accordingto claim 6, wherein the associated fusion enthalpy is lower than 110J/g.
 8. The adduct according to claim 1, wherein the adduct is inspheroidal particle form.
 9. A catalyst component for polymerizingolefins comprising a product of a reaction between a transition metalcompound and a MgCl₂·mEtOH·nH₂O adduct, wherein 3.4<m≦4.4, 0<n≦0.7, theadduct having an X-ray diffraction spectrum comprising at least onediffraction line at each diffraction angle 2θ of 9.3±0.2° and 9.9±0.2°with each diffraction angle being between 5° and 10°, the diffractionline at diffraction angle 2θ of 9.3±0.2° being more intense than thediffraction line at diffraction angle 2θ of 9.9±0.2° being less than 0.4times as intense as the diffraction line at diffraction angle 2θ of9.3±0.2°.
 10. The catalyst component according to claim 9, wherein thetransition metal compound is a titanium compound of formulaTi(OR)_(n)X_(y-n) in which n is between 0 and y; y is a valence oftitanium; X is a halogen and R is an alkyl radical having 1–8 carbonatoms or a COR′ group wherein R′ is an alkyl radical having 1–8 carbonatoms.
 11. The catalyst component according to claim 10, wherein thetitanium compound is selected from TiCl₃, TiCl₄, Ti(OBu)₄, Ti(OBu)Cl₃,Ti(OBu)₂Cl₂, and Ti(OBu)₃Cl.
 12. The catalyst component according toclaim 9, wherein the reaction between the transition metal compound andthe adduct further comprises an electron donor compound.
 13. Thecatalyst component according to claim 12, wherein the electron donorcompound is selected from esters, ether, amines, and ketones.
 14. Thecatalyst component according to claim 12, wherein the electron donorcompound is selected from alkyl or aryl esters of mono or polycarboxylicacids.
 15. The catalyst component according to claim 12, wherein theelectron donor compound is selected from 1,3 diethers of formula:

wherein R⁰, R^(I), R^(II), R^(III), R^(IV) and R^(V), are equal ordifferent from each other, and are hydrogen or hydrocarbon radicalshaving from 1 to 18 carbon atoms, and R^(VI) and R^(VII), are equal ordifferent from each other, and are hydrocarbon radicals having from 1 to18 carbon atoms, optionally with one or more of R—R^(VII) linked to forma cyclic group.
 16. A catalyst component for polymerizing olefinscomprising a product of a reaction between a transition metal compoundand a partially dealcoholated MgCl₂-ethanol adduct obtained by partialdealcoholation of a MgCl₂·mEtOH·nH₂O adduct, wherein 3.4<m≦4.4, 0<n≦0.7,the MgCl₂·mEtOH·nH₂O adduct having an X-ray diffraction spectrumcomprising at least one diffraction line at each diffraction angle 2θ of9.3±0.2° and 9.9±0.2° with each diffraction angle being between 5° and10°, the diffraction line at diffraction angle 2θ of 9.3±0.2° being moreintense than the diffraction line at diffraction angle 2θ of 9.9±0.2°,and the diffraction line at diffraction angle 2θ of 9.9±0.2° being lessthan 0.4 times as intense as the diffraction line at diffraction angle2θ of 9.3±0.2°.
 17. The catalyst component according to claim 16,wherein the partially dealcoholated MgCl₂-ethanol adduct contains from0.1 to 3 moles of ethanol per mole of MgCl₂.
 18. The catalyst componentaccording to claim 17, wherein the partially dealcoholated MgCl₂-ethanoladduct has a porosity ranging from 0.5 to 2 cc/g.
 19. The catalystcomponent according to claim 17, wherein the partially dealcoholatedMgCl₂-ethanol adduct contains from 1 to 3 moles of ethanol per mole ofMgCl₂ and a porosity ranging from 0.15 to 1.5 cc/g.
 20. A catalyst forpolymerizing olefins comprising a product of a reaction between acatalyst component, which comprises a product of a reaction between atransition metal compound and a MgCl₂·mEtOH·nH₂O adduct wherein3.4<m≦4.4, 0<n≦0.7, the adduct having an X-ray diffraction spectrumcomprising at least one diffraction line at each diffraction angle 2θ of9.3±0.2° and 9.9±0.2° with each diffraction angle being between 5° and10°, the diffraction line at diffraction angle 2θ of 9.3±0.2° being moreintense than the diffraction line at diffraction angle 2θ of 9.9±0.2°,and the diffraction line at diffraction angle 2θ of 9.9±0.2° being lessthan 0.4 times as intense as the diffraction line at diffraction angle2θ of 9.3±0.2°.
 21. The catalyst for polymerizing olefins according toclaim 20, wherein the organoaluminum compound is an Al-trialkylcompound.
 22. The catalyst for polymerizing olefins according to claim21, further comprising an external donor.
 23. The catalyst forpolymerizing olefins according to claim 22, wherein the external donoris selected from silane compounds containing at least one Si—OR link,having a formula of R_(a) ¹R_(b) ²Si(OR³)_(c), where a and b are integerfrom 0 to 2, c is an integer from 1 to 3, and the sum (a+b+c) is 4; R¹,R², and R³, are alkyl, cycloalkyl, or aryl radicals with 1–18 carbonatoms.
 24. A process for polymerizing olefins of formula CH₂═CHR⁴, inwhich R⁴ is hydrogen or a hydrocarbon radical having 1–12 carbon atoms,comprising a catalyst for polymerizing olefins comprising a product of areaction between a catalyst component for polymerizing olefinscomprising a product of a reaction between a transition metal compoundand a MgCl₂·mEtOH·nH₂O adduct wherein 3.4<m≦4.4, 0<n≦0.7, the adducthaving an X-ray diffraction spectrum comprising at least one diffractionline at each diffraction angle 2θ of 9.3±0.2° and 9.9±0.2° with eachdiffraction angle being between 5° and 10°, the diffraction line atdiffraction angle 2θ of 9.3±0.2° being more intense than the diffractionline at diffraction angle 2θ of 9.9±0.2°, and the diffraction line atdiffraction angle 2θ of 9.9±0.2° being less than 0.4 times as intense asthe diffraction line at diffraction angle 2θ of 9.3±0.2°, and anorganoaluminum compound.
 25. A catalyst for polymerizing olefinscomprising a product of a reaction between a catalyst component, whichcomprises a product of a reaction between a transition metal compoundand a partially dealcoholated MgCl₂-ethanol adduct obtained by partialdealcoholation of a MgCl₂·mEtOH·nH₂O adduct wherein 3.4<m≦4.4, 0<n≦0.7,the adduct having an X-ray diffraction spectrum comprising at least onediffraction line at each diffraction angle 2θ of 9.3±0.2° and 9/9±0.2°with each diffraction angle being between 5° and 10°, the diffractionline at diffraction angle 2θ of 9.3±0.2° being more intense than thediffraction line at diffraction angle 2θ of 9.9±0.2°, and thediffraction line at diffraction angle 2θ of 9.9±0.2° being less than 0.4times as intense as the diffraction line at diffraction angle 2θ of9.3±0.2°, and an organoaluminum compound.
 26. A process for polymerizingolefins of formula CH₂═CHR⁴, wherein R⁴ is hydrogen or a hydrocarbonradical having 1–12 carbon atoms, comprising a catalyst for polymerizingolefins comprising a product of a reaction between a transition metalcompound and a partially dealcoholated MgCl₂-ethanol adduct obtained bypartial dealcoholation of a MgCl₂·mEtOH·nH₂O adduct wherein 3.4<m≦4.4,0<n≦0.7, the adduct having an X-ray diffraction spectrum comprising atleast one diffraction line at each diffraction angle 2θ of 9.3±0.2° and9.9±0.2° with each diffraction angle being between 5° and 10°, thediffraction line at diffraction angle 2θ of 9.3±0.2° being more intensethan the diffraction line at diffraction angle 2θ of 9.9±0.2°, and thediffraction line at diffraction angle 2θ of 9.9±0.2° being less than 0.4times as intense as the diffraction line at diffraction angle 2θ of9.3±0.2°, and an organoaluminum compound.